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Math Help - I am a newbie. Please help me to solve this problem. I would appreciate your help.

  1. #1
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    I am a newbie. Please help me to solve this problem. I would appreciate your help.

    One person enters the stadium the first mimute, two people the second mimute, three people the third minute, and so on. In how many mimutes will there be 55 people in the stadium?
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  2. #2
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    Quote Originally Posted by maggie
    One person enters the stadium the first mimute, two people the second mimute, three people the third minute, and so on. In how many mimutes will there be 55 people in the stadium?
    Hello,

    you want to know the number of summands in a sum:

    1+2+3+...+n=55\Longrightarrow \frac{1}{2}\cdot n\cdot (n+1)=55

    Expand the LHS of this equation and solve the quadratic equation for n:

    \frac{1}{2}n^2+\frac{1}{2}n-55=0

    You'll get x = -11 or x = 10. (-11) persons are a very ugly sight.
    So the only possible solution for your problem is: 10 persons.

    Greetings

    EB
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  3. #3
    Grand Panjandrum
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    Other copy of this deleted

    Don't make multiple posts of the same question.

    RonL
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  4. #4
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    Thank you for your help. However, my son is 11 years old. I don't think he could understand the fomular you just gave. Do you have another way to show my son to understand easier. Thank you so much.
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  5. #5
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    Quote Originally Posted by maggie
    Thank you for your help. However, my son is 11 years old. I don't think he could understand the fomular you just gave. Do you have another way to show my son to understand easier. Thank you so much.
    Hello, Maggie,

    show your son how to calculate in a table.

    I've attached a diagram to show you what I mean.

    Greetings

    EB
    Attached Thumbnails Attached Thumbnails I am a newbie. Please help me to solve this problem. I would appreciate your help.-summe_n.gif  
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  6. #6
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    Hello Earboth,

    Thank you so much for your help. My son is understanding now. It is much easier for him to understand . Thank you again.
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